Weight training at 13 Good or bad?

Answer 1

You have to be careful weight training at that age, because your bones are still at a formative stage.

Some limited weigh training is fine, but you would be better advised to get for low weight high reps, rather than high weight low reps.

Answer 2

If you are asking if lifting will be effective, it can be. It can also be harmful if you press to hard or too heavy. Lift to tone at this point. If you lift to build, you could adversely affect your growth and development. Concentrate on form and technique.